If action is not available into the controller and html occurs for the action so will rails show error or not?

How file loads? or hierarchy for loading the controller files?(alphabetically loads file)

Use of config.ru?

How routes call to particular action? An idea about routing?

What are cron Jobs?

How to connect multiple databases?

Can a model file connect to some other database in rails? How?

Middleware in rails?

What are alias in rails?

How to create runtime methods?

How to create singleton class? an example in rails? (logs)

What are mixins?

What are virtual attributes?

What are whitelist/strong parameters?

Why we use strong parameters in rails 4? Reason behind that?

What is use of super?

Why we use self?

Why not we use multiple inheritance and method overloading in rails?

How many type of exceptions are in rails?

How to enable you logging on production mode?

Custom validations?

Open classes?

What are the use of initializers?

Is internationalization occurs in rails?

What is rake?

Best practice to define constants?

What are named scope in routing?

What is use of concern in routing?

What is use of transaction method in rails?

What type of threading used in rails 4?

Which javascript library use by default in rails 4?

What is use of assets in rails ?

OOPS :

Ques1: What is a class and object?
Ques2: How will you define a class (Real Time example) ?
Ques3: Why we need to create a class and why objects are created for a class ?
Ques4: What is use of class ?
Ques5: What is polymorphism, inheritance etc. Some basic oops concepts ?